“At 75, mezzo Christa Ludwig has lost nothing of her sharpness. There is little of the diva in her manner. She has presence, of course. You can’t have a career that dominated opera on both sides of the Atlantic for 40 years without that. But, immaculately dressed in a dark-grey trouser suit, the effect is discreet. She once wrote that while she always wanted to be a prima donna, she was “too lazy” for the scandal and circus that went with the role.”